Thermostatic control



w. E. JENKINS ETAL THERMOSTATIC CDNTROL Filed Oct. 29, 1945 MN Mm. mvm.

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Patented Oct. 3, 1950 'rnEnMos'rAric coNTRoL Wayne E. Jenkins and Theodore H. Thiele, Los

Angeles, Calif., assignors, by mesne assignments, to Domestic Thermostat Company, a corporation of California Application October 29, 1945, Serial No. 625,212

6 Claims. 1

The invention relates to thermostatically operated safety valves of the typeV disclosed in U. S. Patent No. 2,322,520, issued to Wayne E. Jenkins on June 22, 1943, and more particularly to the construction and mounting of thebi-inetal thermostat element of such a unit.

An object of the invention is to provide a unit of the character described wherein the bimetal element is so constructed and mounted relative to its associated coacting parts as to better withstand the physical stress, the heating and the flexing to which it is subjected, whereby the unit will be more positive and reliable in its operation, perform its required precision movement with greater dependability, and have a much longer useful life than structures heretofore available` Another object of the invention is to provide construction of the character above which lends itself to large scale mass production on a relatively simple and inexpensive basis in manufacn ture and assembly, and wherein the end item is so formed and assembled as to insure such a den gree of uniformity of the items produced as to substantially eliminate the requirement for factory setting of individual devices to an acceptable tion of the preferred form of the invention which is illustrated in the drawings accompanying and forming part of the specification. It is to be understood, however, that variations in the showing made by the said drawings and description may be adopted within the scope of the invention as set forth in the claims.

Referring to the drawing:

Figure 1 is a view partly in side elevation and partly in cross-section showing a thermostatically operated apparatus regulated by an improved thermostatic control of our invention. Certain of the parts are broken away to shorten the view.

Figure 2 is a perspective view of one type of loi-metal latch.

Figure 3 is a `fragmental sectional view of a modified form of mounting.

Figure l is a fragmental side elevational View of a further modied form of control element and mounting.

Figure 5 is a fragmental side elevational view of still another modification of the control element and mounting therefor.

Figure 6 Vis an end elevational view of the structure shown in Figure 5.

The 1oimetal thermostat control structure of 2 the present invention may he 1used in various types of control devices. IThe device here selected for purposes of illustrating and ldescribing the present invention is of the general type and ,construction disclosed in the above mentioned U.. S. Letters Patent No. 2,322,520 to which reference is made for a more complete showing and description of operating parts not specifically involved in the present invention. The device here shown is a pilot-.operated safety valve positioned in the fuel line to the main burner of a heating appliance, such as a water heater, furnace, or `the "se, and which functions automatically to shut off the flow of fuel to the main burner should the pilot burner, used for igniting the main burner, he accidentally or otherwise extinguished. With reference to Figure l of the drawing, the device comprises a valve housing 'i provided with Van inlet chamber 8, supplied with fuel from a supply pipe 9 and, outlet chamber l l, fitted with an outlet pipe l2 through which fuel may .besupplied to a main burner, not shown. A port I3 in the valve housing 'l provides communication between the chambers a and l and may be opened or closed by a springmressed poppet valve I4 'located in the chamber 8. A control rod i6, coaxially connected with the valve stem il, ,is mounted for movement in tube i8, connected into and projecting from a boss i9 formed on the side of the valve housing, the outer end of the rod terminating within a metallic capsule 2l which is carried by a collar 22 iiXedly secured to the outer end of the tube i8. A bushing 2 3, concentric with the outer end of the control rod it, is provided with a threaded stem 2t engaged in a complementary threaded recess formed in the collar 22. A strip 26 of bimetal, paralleling the control rod It, is secured in one of several ways, which will he presently described, to the sleeve 23 and has a free end formed with a lip `ill inturned toward the axis of the control rod.

A pilot burner is provided, by means of which ignition-of the main burner may he accomplished, which comprises a length oi tubing 2S having an end secured in the boss l2 and paralleling the tube i8 to terminate in closed. end under or `adjacent to `the capsule 2l. Fuel is suppliedto `the pilot tube through a separate fuel inlet 29 and may be ignited at the ports 3l so that the resulting flame will heat the capsule 2l and the bimetal'strip 26 therein. The strip 2t is arranged with its lamination possessing the greater Acoeliicient of heat expansion on the outer or side thereof remote from the axis of the control rod so that heating will Vcause the strip to flex radially ,in the annular recess. structure however to notch out the shoulder 39 in Iorder to provide clearance for the strip 2G which Yaxially traverses it.

inwardly toward the control rod. Thus, if the pilot flame is burning, the lip 2'E of the strip will press against the side of the rod and when the reset button 32 is pulled outwardly, the valve I4 will open to permit fuel flow from the supply line 9 to the main burner and, since the control rod moves correspondingly, the lip 21 will snap over the end of the rod as shown in the drawing and will hold the Valve I4 open thereafter. If, due to any reason, the pilot name should become extinguished, the cooling bimetal strip will flex radially outwardly of the capsule and withdraw the lip 21 thus freeing the control rod and permitting the valve I4 to close under the pressure of its associated spring to effect shutting olf of the flow of fuel to the main burner, which flow may not then be reinstituted until the pilot burner is again ignited and the safety valve is latched in its open position.

, We have successfully employed several different means for attachment of the fixed end of the bimetal strip to the structure of the guide sleeve 23, each of which is functionally identical in that the mounting in no way modifies the flexing action of the strip. In the type of sleeve structure shown in Figure 1, we provide an integral collar 33 in which an annular groove 34 is formed, The bimetal strip associated with this type of mounting is shown in Figure 2 and comprises a pair of integral tabs 36, formed with and extending from the strip 26, which are shaped to circular form and are pressed into the groove 34, the latter being slightly deeper than the width of the tabs so that bordering metal of the groove may be peened over thereinto in effecting a secure lock for the tabs in the groove. In Figure 3, we have shown another method of accomplishing this result. In this case, the collar 3l is a separate piece and is provided with an axial counterbore 38 cooperative, with the extended sleeve 23, to form an annui-ar recess, equivalent to the recess 34,

lfor receiving the tabs 36. The sleeve 23 of course is a tight press t in the bore of the collar 31 and an annular shoulder 39 formed on the sleeve overlies the counterbore 38 and secures the tabs 36 It is necessary in this In Figure 4 we have illusltrated another form of mounting comprising a keyhole-shaped or similarly figured recess 4| which may be end-milled into the side of the sleeve structure 42, which in this case may be a .unitary piece, the end of the bimetal strip 26 being formed with a coextensive tab 43 complevmentary in shape with the recess 4l and fitting invention, it should be particularly noted that,

in all of the anchoring structures shown in the drawing, the bimeta1 strip, as it extends through its nodal point, that is, the plane separating its inactive and actively flexible portions, is coplanary with the inactive and active portions in alignment in contrast to the bent type of strip vshown in the above mentioned patent- Thus no structural alteration in the metal at the so-called nodal point, equivalent to that in the bent types of bimetal strips, is present and full power and senstiveness in the strip is preserved. It will be obvious therefore that, since the combined active and inactive portions of the strip are composed of a single piece of unaltered material, it is possible to turn out the bimetal strips in large quantities with the assurance that the operational characteristics of respective strips will be substantially identical, all other factors being equal. The time-saving value of such a result, in the inspection, calibration and adjustment that is eliminated, will be especially apparent to those who employ volume production in their plants, as will the ease of assembly -provided by the various types of mountings.

We claim:

l. In a thermostatic control device, a movable control rod, a relatively iixed sleeve concentric with said control rod and provided with a concentric recess, a bimetal element disposed adjacent said control rod and having a portion thereof flexible under the application of heat thereto toward said control rod, said element having at one end thereof an offset portion movable during said fiexure into engagement with and to hold said control rod against movement, and said element at the other end thereof having an integral circularly formed anchor portion entering and secured in the recess of said sleeve, and said anchor portion and said flexible portion being joined in a straight line through an intermediate point of exure and with line substantially parallel to said rod.

2. In a thermostatic control device, a movable control rod, a relatively fixed sleeve concentric with said control rod and provided with 'a recess extending longitudinally of and radially entering a peripheral surface of said sleeve, a bimetal element disposed adjacent said control rod and having a portion thereof flexible under the application of heat thereto toward said control rod, said element having at one end thereof an offset portion movable during said flexure into engagement with and to hold said control rod against movement, and said element at the other end thereof having an integral anchor portion thereof complementary to, entering and secure in said recess, and said anchor portion being coextensive and lying in a common plane with said flexible p0rtion of said element.

3. In a thermostatic control device, a movable control rod, a relatively fixed sleeve concentric with said control rod and provided with a recess extending chordally across said sleeve in radially oiiset relation to the axis thereof, a bimetal element disposed adjacent said control rod and having a portion thereof flexible under the application of heat thereto toward said control rod, said element having at one end thereof an offset portion movable during said flexure into engagement with and to hold said control rod against movement, and said element at the other end thereof having an integral anchor portion keyed in said recess, and said anchor portion being co-extensive land. lying in a common plane with said flexible portion of said element.

4. In a thermostatic control device, a movable control rod, a relatively fixed sleeve concentric with said control rod, a collar secured on said sleeve having therein a counterbore cooperative with a portion of the sleeve to form a concentric recess about the control rod axis, a bimetal element disposed adjacent said control rod and having a portion thereof flexible under the application of heat thereto toward said control rod, said element having at one lend thereof an offset porthereof projecting from an end face of said collar and being spring loaded for movement away from said collar face, said collar being formed with a recess opening to said face and having a depth dimension parallel to the axis of said rod, an elongated bimetal element having a relatively i'lxed end portion mounted and secured in lsaid recess and a contiguous nexible portion extending from said end portion with a nodal point atsaid collar face, said flexible portion extending generally parallel to said axis in spaced relation to said rod and swinging to and from said rod from said nodal point in response to change in temperature, the opposite end of said element being bent at substantially right angles to the length thereof in the direction of said rod and having an oifset dimension suflicient to latch over` the outer end of said rod to hold it against outward movement under the influence of said spring loading upon appropriate heating of said element,

said element being subjected in said latched position to longitudinal tensional strain and said flexible portion being joined to said rst end portion in a substantially straight line passing through said nodal point.

6. In a thermostatic control device including a relatively xed collar of annular form and a control rod mounted substantially axially therethrough for longitudinal reciprocation and having one end projecting from an annular end face of said collar, spring means normally urging said rod end outwardly from said collar face, said collar being formed with a substantially circular recess substantially concentric to said rod and opening to said face and having a depth-wise dimension substantially parallel to the axis of said rod, a bimetal element having a substantially annular base portion mounted and secured in said recess with an elongated flexible portion extending therefrom in substantially parallel relation to said axis and joined to said base portion in a nodal point for relative flexure of said elongated Iportion, said elongated portion constructed to swing from said nodal point to and from said rod in response to change in temperature, the opposite free end of said element being bent at'substantially right angles t0 the length thereof in the direction of said rod to latch over said outer. rod end for holdingsaid rod against outward movement under the influence of said spring means,

said element being subjected in latched position to longitudinal tensional strain and said elongated ilexible portion being joined to said annular base portion in a substantially straight line passing through said nodal point.

WAYNE E. JENKINS. THEODORE I-I. THIELE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 265,239 Brown Oct, 3, 1882 1,766,608 Crews June 24, 1930 2,204,890 Gathercole June 18, 1940 2,301,070 y Meyers NOV. 3, 1942 2,322,520 Jenkins June 22, 1943 

